linux-kernel - Re: [PATCH] drm/bridge: adv7511: Fix low refresh rate selection

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Message-ID: <20190511193226.GO13043@pendragon.ideasonboard.com>
Date:   Sat, 11 May 2019 22:32:26 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Matt Redfearn <matt.redfearn@...nci.com>
Cc:     Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Matthew Redfearn <matthew.redfearn@...nci.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jia-Ju Bai <baijiaju1990@...il.com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        David Airlie <airlied@...ux.ie>,
        Sean Paul <seanpaul@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>
Subject: Re: [PATCH] drm/bridge: adv7511: Fix low refresh rate selection

Hi Matt,

Thank you for the patch.

On Wed, Apr 24, 2019 at 01:22:27PM +0000, Matt Redfearn wrote:
> The driver currently sets register 0xfb (Low Refresh Rate) based on the
> value of mode->vrefresh. Firstly, this field is specified to be in Hz,
> but the magic numbers used by the code are Hz * 1000. This essentially
> leads to the low refresh rate always being set to 0x01, since the
> vrefresh value will always be less than 24000. Fix the magic numbers to
> be in Hz.
> Secondly, according to the comment in drm_modes.h, the field is not
> supposed to be used in a functional way anyway. Instead, use the helper
> function drm_mode_vrefresh().
> 
> Fixes: 9c8af882bf12 ("drm: Add adv7511 encoder driver")
> Signed-off-by: Matt Redfearn <matt.redfearn@...nci.com>

Wow, a 4.5 year old bug fix, nice :-)

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> ---
> 
>  drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> index 85c2d407a52..e7ddd3e3db9 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> @@ -747,11 +747,11 @@ static void adv7511_mode_set(struct adv7511 *adv7511,
>  			vsync_polarity = 1;
>  	}
>  
> -	if (mode->vrefresh <= 24000)
> +	if (drm_mode_vrefresh(mode) <= 24)
>  		low_refresh_rate = ADV7511_LOW_REFRESH_RATE_24HZ;
> -	else if (mode->vrefresh <= 25000)
> +	else if (drm_mode_vrefresh(mode) <= 25)
>  		low_refresh_rate = ADV7511_LOW_REFRESH_RATE_25HZ;
> -	else if (mode->vrefresh <= 30000)
> +	else if (drm_mode_vrefresh(mode) <= 30)
>  		low_refresh_rate = ADV7511_LOW_REFRESH_RATE_30HZ;
>  	else
>  		low_refresh_rate = ADV7511_LOW_REFRESH_RATE_NONE;

-- 
Regards,

Laurent Pinchart